Soft magnetic properties and giant magneto-impedance effect of Fe-Zr-Nb-B-Cu ribbons

The soft magnetic properties and the giant magneto-impedance (GMI) effect h ave been studied in Fe84Zr3.5Nb3.5B8Cu ribbons. The annealed samples with n anocrystalline structure show excellent soft magnetic properties and induce d transverse anisotropy. The effective permeability is found to reach a max imum for the sample annealed at 923 K for 20 min. The maximal magneto-imped ance ratio Delta Z/Z (Delta Z/Z = (Z(H) - Z(H-max))/Z(H-max)) of about 383% and the maximal sensitivity (i.e. the maximal value of the derivative of t he Delta Z/Z-H-L curve) of about 0.91% (A m(-1))(-1) (72% Oe(-1)) are measu red at frequency f = 2.5 MHz for the same sample. The excellent soft magnet ic properties and the induced transverse anisotropy are the basis of obtain ing the sensitive magneto-impedance response. The intrinsic mechanism of th e influence of the soft magnetic properties on the GMI effect is discussed briefly.